Lockmaster LM902 Swing Gate Opener Circuit Board

Hi all,
Having issues with my auto gate opener, It is brand new but unfortunately i never installed it until a year later and it has just fallen outside of the warranty period.
The system consists of 2 gate openers and a rf control board.
After install i tested gate number 1 which worked ok a couple of times while i was trying to set the limits but then appeared to go faulty.
Now all it does is close for 1 second, then open for 1 second then stops.
Gate number 2 is set up and working correctly.
I am an electrician but my electronics knowledge is limited and I have spent hours on these damn things.
Any help would be greatly appreciated.

Hi user139

Thank you for contacting the Digi-Key Forum. Most likely everything is working on the board electronically speaking. Although this is not a product we carry, there are a few things to point out that may help however:

  1. There are two (blue and yellow) potentiometers, these may be for setting a time adjustment.
  2. The limit switches may have to be manually set when initial programming of the gate is being performed, I would suggest reading the manual if you haven’t already and make sure there isn’t some kind of initial limit switch programming that needs to be re-done for gate1. Sometimes these are electronically timed (initially set by toggling the limits), and the limit switches are only for a safety backup.
  3. Gate 1 may have a physical interference or defect. You may swap the gates around or remove them completely and see what the result is on your timer, or consult with the manufacturer of the device.

Hello user139:

I shared your post with others in my department and got a few different suggestions for you, posted below.

\ 45x45 AaronRollens DigiKey Employee
December 9

I will firstly say that I have not worked with these, this is just a wild grasp at pulling something out of the air. The gate opens, then it closes, that means that works. The issue must be in the signal portion of things. I could easily see a manufacturer placing a protection in the system that would stop it in the event the signal to activate voltage is held on. If they didn’t their is potential to see a gate opening and closing indefinitely and that would be more troublesome.

You will want to verify that signal is correct and functioning properly.

\ 45x45 Travis_Foss DigiKey Employee
December 9

On the one that I worked with, you would need to set the stall force of the gate opener, otherwise it would stall out prior to the gate being fully opened.

Here is a link to the manual that explains the process on this opener, LockMaster LM901 User Manual (Page 20 of 33) | ManualsLib

\ 45x45 David_1528 Applications Engineer
December 9

I have never seen one of these up close, so I don’t really know what these look like or how they operate. If it’s anything like a garage door opener, they have an adjustable setting which senses back force on the door, so that one injure anyone. If it has a similar mechanism, maybe that needs adjustment.

Similarly, maybe a “closed” sensor or wiring from it is faulty. If so, perhaps it tries to close, doesn’t get a confirmation, and opens again. You should check that wiring carefully, and if that appears good, maybe you could switch sensors from the working unit and see if the problem persists.